Gut microbiome in allogeneic hematopoietic stem cell transplantation and specific changes associated with acute graft vs host disease

Table 2 Gut microbiome diversity, composition and function changes in patients receiving allogeneic hematopoietic stem cell transplantation procedure and developing acute graft versus host disease

Ref.	Sequencing technology	Change in diversity	Changes in composition	Change in functions
Ilett et al[10] (150 patients)	Shotgun metagenomic	Decrease in gene richness during the early post-aHSCT period in patients with aGVHD	Decrease in Akkermansia muciniphila, Blautia obeum, Blautia hydrogenotropica, and Blautia hansenii during the early post-aHSCT period in patients with aGVHD	Increase in toxin named PetZ, that triggers bacterial autolysis in pathological bacteria during the pre-aHSCT and the early post-aHSCT period in patients with aGVHD
Holler et al[27] (31 patients)	16S rRNA V3 sequencing		Increase in enterococci in patients who subsequently developed acute GVHD
Galloway-Peña et al[22] (44 patients)	16S rRNA V4 sequencing	Lower Shannon diversity index in fecal samples collected at the time of engraftment in patients with subsequent aGVHD	Coriobacteriia negatively correlated with the incidence of acute GVHD	Fecal metabolites (Fecal indole and butyrate levels determined using liquid chromatography tandem mass spectrometry) associated with acute GVHD
Liu et al[24] (57 patients)	16S rRNA V4 sequencing	High gut microbiota donor diversity associated with decreased risk of aGVHD in recipient
Doki et al[29] (107 patients)	16S rRNA V4 sequencing		Higher abundance of phylum Firmicutes in samples collected before aHSCT in patients with acute GVHD
Golob et al[23] (66 patients)	16S rRNA V3-V4 sequencing	Diversity significantly lower in patients with GVHD	Butyricicoccus, Bacteroides luti, Bacteroides thetaiotaomicron, Bacteroides ovatus, and Bacteroides caccae negatively correlated with subsequent acute GVHD, Rothia mucilaginosa, Solobacterium moorei, Veillonella parvula, and Bacteroides dorei positively correlated with subsequent onset of GVHD
Michonneau et al[31] (99 patients)	Metabolomics			Significant decrease in tryptophan metabolites, including microbiota-produced compounds, such as 3-indoxyl sulfate, indoleacetate, indoleacetylglutamine, and indolepropionate in patients with aGVHD
Payen et al[25] (70 patients)	16S rRNA V3-V4 sequencing	Decreased diversity in acute GVHD	Lachnoclostridium, Blautia, Sellimonas, Anaerostipes, Faecalibacterium, Flavonifractor, Erysipelatoclostridium and Lactococcus negatively associated with subsequent acute GVHD

HSCT: Hematopoietic stem cell transplantation; GVHD: Graft-versus-host disease.